An Isochrone Database and a Rapid Model for Stellar Population Synthesis

Abstract

We first presented an isochrone database that can be widely used for stellar population synthesis studies and colour-magnitude diagram (CMD) fitting. The database consists of the isochrones of both single star and binary star simple stellar populations (ss-SSPs and bs-SSPs). The ranges for the age and metallicity of populations are 0--15 Gyr and 0.0001--0.03, respectively. All data are available for populations with Salpeter IMF and Chabrier IMF. Then based on the isochrone database, we built a rapid stellar population synthesis (RPS) model and calculated the high-resolution (0.3 AA) integrated spectral energy distributions (SEDs), Lick indices and colour indices for bs-SSPs and ss-SSPs. In particular, we calculated the UBVRIJHKLM colours, ugriz colours and some composite colours that consist of magnitudes on different systems. As an example for applying the isochrone database for CMD fitting, we fitted the CMDs of star clusters M67 and NGC1868 and obtained their distance moduli, colour excesses, stellar metallicities and ages. The results showed that the isochrones of bs-SSPs are closer to those of real star clusters. The isochrone database, colours, Lick indices of populations can be downloaded via http://www.ynao.ac.cn/~bps/zhongmu/download.htm